Core drill



Oct. 20, 1936.

J. H. HOWARD El AL CORE DRILL Filed'Aug. 7, 1953 2 Sheets-Sheet 1 3 m r a w n /MK. A n: 4 f .5 i a a B w u a Oct. 20, 1936. 1 .1. H. HOWARD ET AL 2,058,154

CORE DRILL Filed Aug. 7, 1953 2 Sheets-Sheet 2 "/m enfons John [7. Harvard ll/fred 6'. 6077004! P [I M f Afforhe I I Patented Get. 20, 1936 UNITED STATES PATENT OFFICE CORE DRILL Application August 7, 1933, Serial No. 684,018 2 Claims. (crass-'12) This invention relates to a well drilling tool, and relates more particularly to a core drill for obtaining samples or cores of the earth formation. It is a general object of the invention to provide a simple, practical and particularly effective core drill.

It has been found desirable to mount the inner core receiving barrel of a rotary core drill in a manner so that it is free to remain stationary or not rotate with respect to the core during the drilling operation. In the core drills that have been introduced having fioating" inner barrels that may be held against rotation through contact with the core during the rotation of the drills, the inner barrels are usually rotatably supported from their upper ends. Rotatably supporting the inner barrel of a core drill from its upper end greatly complicates the construction, and necessitates the provision of guiding means and packing means at the lower end of the barrel to prevent circulation fluid from washing away the core. The core receiving inner barrels of the various classes of core drills that have been introduced have valves or other elements connected to their upper ends by screw threads and have their lower ends threadedly connected with the bit head or other support. The provision of screw threads on the inner barrel of a core drill requires that the barrel have comparatively heavy or thick walls. Heavy inner barrels are expensive, and materially reduce the diameter of the cores that may be taken by the drill. Further, floating inner barrels having thick walls are very heavy and are not readily held against rotation by engagement with the core, and often rotate with the drill.

Another object of the invention is to provide a core drill including a floating inner barrel having thin walls whereby it is operable to receive a core of maximum diameter and is extremely light in weight and inexpensive of manufacture.

Another object of the invention is to provide a core drill having an inner barrel for receiving the core that is entirely without screw threads so that it may have very thin walls. As the inner barrel of the drill provided by the present invention has no threads cut in it and does not have to be handled by tongs or other. turning tools, it may have very thin walls.

Another object of the invention is to provide a core drill including a simplified and improved valve assembly for the inner barrel that is dependably and efiectively removaly attached to the upper end of the barrel without the employment of screw threads.

Other objects and features of the invention will be better and fully understood from the following detailed description of a typical form and application of the invention, throughout which description reference is had to the-accompanying drawing, in which:

Fig. 1 is a side elevation of the core drill provided by the present invention with certain parts broken away to appear in vertical cross section. Fig. 2 is an enlarged side elevation of the valve means embodied in the core drill with a portion broken away to appear in vertical cross section. Fig. 3 is a top or plan view of the valve illustrated in Fig. 2. Fig. 4 is an enlarged fragmentary detailed sectional view taken substantially as indicated by line 4-4 on Fig. 5. Fig. 5 is an enlarged horizontal detailed sectional view taken as indicated by line 5-5 on Fig. 1. Fig. 6 is an enlarged vertical detailed sectional view of the core catcher embodied in the drill.

The rotary core drill provided by the present invention includes generally, an outer barrel In, a bithead H on the lower end of the outer barrel I0, an inner barrel [2 for receiving the core cut by the bit head, a core catcher l3, and

a removable valve H on the upper end of the inner barrel l2.

The outer barrel I0 is anelongate tubular structure adapted to be attached to the lower end of a well drilling string. The outer barrel l0 includes a tubular main section l5 provided at its upper end with a sub I6 having a tapered screw threaded pin I! for facilitating connection of the barrel with the drilling string. A sub I8 is threaded on the lower end of the section l5 and carries a bit head sub 19.

The bit head I I is attached to the lower end of the sub l9 and is provided to make an annular cut in the earthformation. I The bit head II includes a tubular shoe or body having circumferentially spaced cutting blades. Eachof the cutting blades includes a pilot portion 2| and a reaming portion 22. The pilot portions 2| of the cutting blades extend downwardly directly below the lower end of the bit head body 20 and out a comparatively narrow annular channel in the formation. The reaming portions 22 of the cutting blades project substantially radially from the bit head body and operate to cut or enlarge the bore to size. The cutting blades formed as just described prevent excessive washing away of the core. The bit head shoe or body 20 is provided at its upper end with a screw threaded socket 23 for receiving the pin on the lower end of the sub I9 and the central opening 24 in the body 20 is operable to pass the core cut by the blade portlons 2|. An annular recess 25 is provided in the wall of the opening 24 at the lower end of the socket 23. The recess 25 rotatably carries the lower end of the inner barrel I2 and the core catcher l3, as will be subsequently described.

Two vertically spaced upwardly facing shoulders 26 and 21 are provided on the walls of the recess 25. The bottom or lower end 26 of the recess 25 constitutes a third upwardly facing shoulder in the bit head body 20. The intermediate shoulder 21 is flat and is inclined downwardly and inwardly.

The inner barrel I2 is arranged longitudinally in the outer barrel l0 and is provided to receive the core cut by the bit head II. It is an important feature of the present invention that the inner barrel I2 is rotatably supported in the bit head body 20 in a manner so that it may be held against rotation through contact with the core during rotation of the drill. The inner barrel I 2 is an elongate tubular member extending from the recess 25 in the bit head to a point adjacent the sub I6. The lower end of the inner barrel I2 is open to receive the core while the upper end of the barrel I2 is closed by the valve means I4. In accordance with the present invention, the inner barrel I2 is not threaded at any point and therefore may have comparatively thin walls, as its walls do not have to carry tapered threads and do not have to be sufliciently rigid to withstand handling by wrenches, tongs, or other turning tools. It will be obvious that the inner barrel I2 having thin side walls allows the drill to be proportioned to cut and receive a core of maximum diameter with respect to the external diameter of the drill. Further, the thin walled inner barrel I2 is light in weight and inexpensive. The inner barrel |2 may be in the nature of a length of tubing of uniform diameter.

A ring or enlargement 29 is provided on the lower end of the inner barrel I2 to cooperate with the bit head body 20. The enlargement 29 is preferably welded to the barrel I2 and surrounds the lower end portion of the barrel. The enlargement 29 projects downwardly from the lower end of the inner barrel |2 in the upper portion of the recess 25 and its lower end is adapted to 1'0- tatably bear on the shoulder 26 to support the inner barrel I2 on the bit head body 20. Efiective bearing means is provided for transmitting upward thrusts from the inner barrel II to the sub I9 in the event engagement with the core holds the inner barrel I2 up in the drill. A hardened bushing ring 30 is pressed in an annular recess 3| in the lower end of the sub IS. The upper portion of the barrel enlargement 29 extends into the bushing ring 30 and a bushing ring 32 is provided on the enlargement 29 to rotatably bear against the lower end of the ring 30. An internal annular recess 33 is provided in the lower end portion of the inner barrel enlargement 29 to carry or receive the upper part of the core catcher I3. It is to be particularly noted that the inner barrel I2 is rotatably can'ied entirely within the body 26 of the bit head The means for rotatably supporting the inner barrel I2 is more fully described and claimed in our divisional application for Letters Patent entitled Core drill, Serial Number 709,460, filed February 2, 1934.

The improved core catcher i3 is rotatably mounted in the bit head I I so that it may be held against rotation relative to the core. The core catcher I3 includes an annular. body rotatably mounted in the recess 25 between the shoulder 2 6 and the upper end of the recess 33. The body of the core catcher I3 includes two rings, an outer ring 35 and an inner ring 36. The rings 35 and 36 are telescoped one within the other and have inclined hearing or cooperating faces 31. The opening 36 in the core catcher body is in vertical register and alignment with the opening 24 of the bit head and is operable to readily pass the core. Circumferentially spaced vertical slots 39 are providedin the inner ring 35 of the core catcher and vertical slots 40 are provided in the lower end of the outer ring 35 in vertical alignment with the slots 39. Core engaging and supporting dogs 4| are pivotally mounted in the slots 39 and protrude outwardly through the slots 40.

The invention provides novel means for pivotally supporting the core engaging dogs 4|. Pins 42 extend through transverse openings in the dogs 4| and project from opposite sides of the dogs to extend into a groove 43 in the periphery of the inner body ring 36. The groove 43 is annular and is partially circular or cylindrical in cross section. The projecting ends of the dog supporting pins 42 are flattened as at 41 and cooperate with the walls of the groove 43 to positively prevent rotation of the pins. The rings 35 and 36 of the core catcher body are securely connected together in a manner to prevent shifting or displacement of the dog carrying pins 42. Rivets 44 extend through radial openings in the rings 35 and 36 to dependably connect the rings. The rivets 44 are preferably positioned adjacent the opposite ends of the dog carrying pins 42 to effectively prevent shifting of the pins. When it becomes desirable or necessary to replace the dogs 4|, the rivets 44 may be drilled out to permit the disconnection of the rings 35 and 36, thereby allowing the removal of the pins 42 and dogs 4|. While we have shown the rings 35 and 36 connected together by rivets 44, it is to be understood that these elements may be connected by screws or other equivalent means without departing from the principles of the invention. a

The dogs 4| of the core catcher are adapted to project into the core passing opening 38 of the core catcher body to engage and support the core.

The undersides 45 of the dogs 4| are inclined upr wardly and inwardly and the dogs are provided with sharp outer edges 46. The exposed portions of the inclined shoulder 31 of the outer ring 36, at the slots 39, allow the dogs 4| to pivot upwardly and outwardly to positions entirely clear of the core passing opening 38. It is a feature of the present invention that the active or core engaging inner portions of the dogs 4| are of different lengths. One or more comparatively short dogs 4| are provided to support and retain cores of hard earth formations. The dogs 4|, in being comparatively short, have effective angles of attack or engagement so that it is practically impossible for a hard core of any appreciable diameter to slip through the core catcher when the drill is raised. One or more dogs 4| b of medium length are provided on the catcher for supporting and retaining cores of soft formation which are quite' frequently undersized in diameter. The

dogs 4| b of medium length are operable to effectively grip and support cores that the smaller dogs 4| are not capable of properly contacting. One or more long dogs 4| are provided in the catcher for supporting and catching cores which are badly broken or shattered. The longer dogs 4| are operable to'prevent badly broken cores from sitting or passing through the core catcher as the drill-is raised. In the particular arrangement and assembly illustrated in the drawings, there are two diametrically opposite dogs 4 I, two diametrically opposite dogs 4|, and two diametrically opposite dogs 4|".

The invention includes means for yieldingly urging the pivoted core gripping dogs inwardly to engage or cooperate with the core. Notches 48 are provided inthe outer ends of the dogs 4| to intersect the opening passing the pins 42. Helical torsional springs 49 surround the pins 42 within the notches 48. Each spring 49 has an end bearing against a shoulder 31 and an end bearing against the outer wall of a notch 48, and is under a torsional strain so as to normally yieldingly urge the core gripping dog downwardly and outwardly into the core passing opening 38. The notches 48 carrying the springs 49 are spaced between the opposite vertical sides of the dogs 4| so that the sides of the dogs are operable to bear against the side walls of the slots 39. Means is provided for supporting the pivoted end portions of the dogs 4| when the dogs are carrying the core. Each dog 4| is provided with a fiat face or shoulder 59 operable to bear against the lower end 5| of a slot 39, and is provided with a shoulder 52 for bearing upwardly against the upper wall 53 of a slot 40. The bearing shoulders 50 and 52 of the dogs 4| are spaced substantial distances apart around the axis of pivotal movement of the dogs so that their engagement with the seats 5| and 53 dependably holds the dogs against turning movement when they are in the extended or down positions supporting the core. The body of the core catcher l3 has limited longitudinal movement in the recess 25 between the shoulder 28 and the upper wall of the recess 33. Cam faces 54 are provided on the protruding outer parts of the dogs 4| that are adapted to cooperate with the inclined shoulder 21 upon upward movement of the bit head relative to the core catcher to urge or pivot the dogs inwardly and downwardly in the opening 38. This camming engagement of the faces 54 with the shoulder 21 aids the action of the springs 49 and insures the positive inward pivoting of the dogs. The core catcher l3 forms the subject of our divisional application for Letters Patent entitled Core catcher Serial Number 709,461, filed February 2, 1934.

The present invention provides means for circulating the drilling fluid or rotary mud directly from the annular space S between the barrels l and- I2 through passages in the bit head body 20 to discharge at the forward faces of the cutting blades. The rotary mud or circulation fluid is pumped downwardly through the drilling string and flows downwardly through the annular space S between the two barrels. Downwardly and outwardly inclined ports 60 are provided in the enlargement 29 of the inner barrel to carry the fluid from the space S to an annular groove or channel 6| in the bit head body 20. The annular channel 6| is provided to distribute the fluid to vertical discharge passages 62 in the bit head body 29. The passages 52 discharge downwardly at the lower end of the bit head body 20 immediately in front of the cutting blades of the head. The flow of the circulation fluid does not in any way interfere with the freedom of the inner barrel i2 and the core catcher |3 to remain stationary relative to the core during drilling. The fluid that may possibly leak from the ports 69 and channel 6| to the recess 25 merely flushes the core catcher,

the forward faces of the cutting blades.

thereby maintaining its freedom of movement. The discharge ports 62 are preferably rectangular in horizontal cross-section and their outer sides are closed by replaceable plates 63.

The valve I4 is provided on the upper end of the inner barrel l2 to permit the escape of liquid from the barrel as the core enters the barrel and to prevent the circulation fluid from passing downwardly into the upper end of the inner barrel. The valve assembly I4 is removable from the barrel I2 to permit the attachment of the device fully described and claimed in our co-pending application Serial Number 684,019, filed on an even date herewith, entitled Pressure head for core barrels. It is a feature of the invention that the valve I4 is removably attached to the upper end of the inner barrel l2 without the employment of screw threads. The valve I4 includes a disc I0 adapted to removably fit in the upper end portion of the barrel. The disc I0 is provided with a central vertical opening II which carries a valve seat I2. A ball valve I3 is operable'to cooperate with the seat I2 to prevent the down flow of fiuid through the opening II. A perforated cage I4 carries the valve 13. A plurality of circumferentially spaced lugs I5 is provided on the periphery of the disc I0 and are adapted to be passed into vertical slots I6 in the upper end of the inner barrel I2. In the preferred form of the invention illustrated in the drawings, an enlarged annular member 18 is welded on the upper end of the inner barrel I2, and the slots I6 are provided in this member. The slots I6 are adapted to readily pass the lugs I5 and have lateral notches I9 at their lower ends for receiving the lugs I5. The disc I0 is adapted to be inserted in the member I8 so that the lugs I5 pass downwardly through the slots 16. The disc may then be turned to position the lugs I5 in the notches I8.

A latch 80 is pivoted on the upper end of the disc I0 and is adapted to be swung downwardly to occupy a slot I6 and thereby prevent the lugs I5 from leaving the notches I9 so that the disc I0 cannot be turned or displaced. The latch 89 is sufficiently long and of sufiicient thickness so that it cannot swing out of the slots I6 when the inner barrel is within the outer barrel I0. Vertical reinforcing ribs 8| are provided on the portions of the member I8, provided with the notches I9. The ribs 8| extend downwardly below the lower end of the member I8 to reinforce the weld connecting the member with the barrel I2. The lower portions 82 of the ribs 8| are increased in thickness to engage the interior of the outer barrel III in the event that the inner barrel sways, thereby eliminating the possibility of the member I8 becoming bent between its slots I6. Radial guide plates or webs 84 are provided on the upper end of the disc Ill and are attached tothe valve cage I4. The webs 84 form effective guides on the inner barrel I2.

During operation, the drill is rotated on the lower end of a string of drill pipe in the usual manner. Circulation fluid is continuously pumped down through the drilling string and discharges from the lower ends of the ports 62 at The pilot portions 2| of the cutting blades make a comparatively narrow annular channel in the formation cutting a core which is received by the opening 24 and the inner barrel I2. The reaming portions 22 of the blades enlarge the bore and cut it to size as the drilling continues. The comparatively narrow channel formed by the pilot portions 2| of the cutting blades does not permit the major flow of thecirculation fluid to directly wash against the core. As the core enters the drill, the gripping dogs ll are pivoted upwardly into the slots 39. The springs 49 acting on the dogs ll yieldingly urge the dogs against the core so that the core catcher body is held against rotation. As described above, the core catcher is freely rotatably mounted in the recess 25 and therefore may be held against rotation during the drilling operation. As the core catcher does not rotate, the gripping dogs ll do not cut or tear up the core and are not seriously worn through contact'with the core. Further, as the core catcher may not rotate with respect to the core, there may be only slight clearance between the wail of the opening 38 and dogs ll with the core so that there is little danger of the core slipping back through the core catcher when the drill is removed from the well. Thecore while being formed, is free to pass upwardly into the inner barrel l2 and its frictional engagement with the inner barrel may hold the inner barrel against turning. The inner barrel I2 is light in weight, and is freely rotatable at its lower end within the bit head i I so that its contact with the core results in it being held against turning. As the walls of the inner barrel l2 are very thin, the drill may be proportioned to cut and obtain a core of maximum diameter. The valve 13 may open during the drilling to permit the escape of fluid that may be trapped in the upper end of the inner barrel i2. The valve 13 is normally closed to prevent the circulation fluid' from flowing downwardly into the inner barrel I2. The projecting enlarged portions 82 of the ribs 8| operate to prevent excessive swaying of the inner barrel without in any way interfering with the downward flow of the circulation fluid between the barrels l0 and I 2. The latch 80 looks the lugs in the notches 19 so that the disc 10 cannot become displaced from the inner barrel iii.

The rotatable mounting of the inner barrel l2 and the rotatable mounting of the core catcher l3 are simple and do not complicate the construction as the circulation fluid is diverted through the ports to the bit head channel 6| without necessitating the provision of ports etc., in the mountings. The valve I4 is readily removable from the inner barrel at the derrick to permit the connection of the pressure head with the barrel. The core catcher I3 is particularly eflective as its dogs port any kind of core. The short dogs 4| are adapted to dependably grip and carry cores of hard earth formations, while the medium dogs 4| are adapted to retain the cores of softer forare operable to catch and supportant, as it provides for the dependable bracing and supporting of the dogs when they are carrying a core. The spaced bearing faces 50 and 52 of the dogs are operable to cooperate with the shoulders on the core catcher body when the dogs are in their down position to positively limit further downward pivoting. The cam faces '54 of the core gripping dogs cooperate with the shoulder 21 of the bithead body to cause the positive downward pivoting of the gripping dogs when the drill is raised. The core drill provided by the present invention is particularly simple and inexpensive of construction and is operable to .efiectively and dependably obtain cores of large diameters.

Having described only a typical form and application of our invention, we do not wish to be limited or restricted to the specific form and application herein described, but is to be considered as including any variations or-modifications that may appear to those skilled in the art or fall within the scope of the following claims.

Having described our invention, we claim:

1. In a core drill, an outer barrel, a bit head on the lower end of the outer barrel, an inner barrel within the outer barrel for receiving a core, there being a bayonet slot in the upper end of the inner barrel, a member adapted to be inserted in'the upper end of the inner barrel, a projection on the member adapted to cooperate with the slot to detachably connect the member to the inner barrel, a latch pivoted on the member and adapted to extend into the slot to prevent displacement of the projection, the latch being proportioned and related to the outer barrel so that the outer barrel prevents it from leaving the slot, there being a passage in the member, and a valve for controlling the flow through the passage.

2. An assembly for arrangement in the outer barrel of a core drill including a tubular thinwalled body having spaced bayonet slots in its upper end portion, reinforcing ribs on said portion at the slots, a valve carrier for arrangement on the upper end of the body, lugs on the carrier for cooperating with the slots, and releasable means locking the lugs in the slots.

JOHN H. HOWARD. ALFRED C. CATLAND. 

